U.S. patent application number 09/954457 was filed with the patent office on 2002-02-14 for method of making high refractive index ophthalmic device materials.
Invention is credited to LeBoeuf, Albert R..
Application Number | 20020019492 09/954457 |
Document ID | / |
Family ID | 26767910 |
Filed Date | 2002-02-14 |
United States Patent
Application |
20020019492 |
Kind Code |
A1 |
LeBoeuf, Albert R. |
February 14, 2002 |
Method of making high refractive index ophthalmic device
materials
Abstract
Disclosed is a two-step method of making soft, high refractive
index, acrylic ophthalmic device materials. In the first step, a
copolymer containing pendant oxirane groups is formed by
copolymerizing one or more aryl acrylic hydrophobic monomers with
one or more compounds of the formula 1 wherein X is H or CH.sub.3;
and n is 1-4. In the second step, the copolymer containing pendant
oxirane groups formed in the first step is reacted with a compound
of the formula W-T-H wherein W is H, CH.sub.3(CH.sub.2).sub.a, or
Z(OCH.sub.2CH.sub.2).sub.b; a is 0-3; b is 1-5; Z is H, or
CH.sub.3(CH.sub.2).sub.p; p is 0-3; and T is O, NH, S; provided
that if T.noteq.O, then W.noteq.H.
Inventors: |
LeBoeuf, Albert R.;
(Burleson, TX) |
Correspondence
Address: |
ALCON RESEARCH, LTD.
R&D COUNSEL, Q-148
6201 SOUTH FREEWAY
FORT WORTH
TX
76134-2099
US
|
Family ID: |
26767910 |
Appl. No.: |
09/954457 |
Filed: |
September 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09954457 |
Sep 17, 2001 |
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09283590 |
Apr 1, 1999 |
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60082833 |
Apr 23, 1998 |
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Current U.S.
Class: |
525/327.3 ;
525/337; 525/344; 525/350; 525/353; 525/379; 525/384; 623/6.56;
623/6.58; 623/6.59 |
Current CPC
Class: |
C08F 220/1808 20200201;
G02B 1/043 20130101; C08F 220/1809 20200201; G02B 1/043 20130101;
C08L 33/14 20130101; C08F 220/1809 20200201; C08F 220/325 20200201;
C08F 222/102 20200201; C08F 220/1809 20200201; C08F 220/325
20200201; C08F 222/102 20200201 |
Class at
Publication: |
525/327.3 ;
525/337; 525/384; 525/344; 525/353; 525/350; 525/379; 623/6.56;
623/6.58; 623/6.59 |
International
Class: |
C08F 016/26 |
Claims
I claim:
1. A method of preparing an ophthalmic device material comprising
the steps of a) forming a copolymer having pendant oxirane groups
by free radical copolymerization of a composition comprising (i)
one or more aryl acrylic hydrophobic monomers of the formula
5wherein: X is H or CH.sub.3; m is2-4; Y is nothing, O, S, or NR
wherein R is H, CH.sub.3, C.sub.nH.sub.2n+1(n=1-10)
iso-OC.sub.3H.sub.7, C.sub.6H.sub.5, or CH.sub.2C.sub.6H.sub.5; and
Ar is C.sub.6H.sub.5 which can be unsubstituted or substituted with
H, CH.sub.3, C.sub.2H.sub.5, n-C.sub.3H.sub.7, iso-C.sub.3H.sub.7,
OCH.sub.3, C.sub.6H.sub.11, Cl, Br, C.sub.6H.sub.5, or
CH.sub.2C.sub.6H.sub.5; and (ii) a total of about 30% by weight or
less of one or more compounds of the formula 6wherein X is H or
CH.sub.3; and n is 1-4; and (b) reacting the copolymer containing
pendant oxirane groups formed in step (a) with one or more
compounds of the formula W-T-H (III) wherein W is H,
CH.sub.3(CH.sub.2).sub.a, or Z(OCH.sub.2CH.sub.2).sub.b; a is0-3; b
is 1-5; Z is H or CH.sub.3(CH.sub.2).sub.p; p is 0-3; and T is O,
NH, S; provided that if T.noteq.O, then W.noteq.H.
2. The method of claim 1 wherein m is 2-4, Y is nothing or O, and
Ar is phenyl in formula I.
3. The method of claim 1 wherein the one or more aryl acrylic
hydrophobic compounds of formula I are selected from the group
consisting of 2-phenoxyethyl acrylate; phenyl acrylate; benzyl
acrylate; 2-phenylethyl acrylate; 3-phenylpropyl acrylate;
3-phenoxypropyl acrylate; 4-phenylbutyl acrylate; 4-phenoxybutyl
acrylate; 4-methylphenyl acrylate; 4-methylbenzyl acrylate;
2-2-methylphenylethyl acrylate; 2-3-methylphenylethyl acrylate;
2-methylphenylethyl acrylate; 2-phenoxyethyl methacrylate; phenyl
methacrylate; benzyl methacrylate; 2- phenylethyl methacrylate; 3-
phenylpropyl methacrylate; 3-phenoxypropyl methacrylate;
4-phenylbutyl methacrylate; 4-phenoxybutyl methacrylate;
4-methylphenyl methacrylate; 4-methylbenzyl methacrylate;
2-2-methylphenylethyl methacrylate; 2-3-methylphenylethyl
methacrylate; and 24-methylphenylethyl methacrylate.
4. The method of claim 1 wherein the total amount of the one or
more aryl acrylic hydrophobic compounds of formula I is about 60%
by weight or greater.
5. The method of claim 1 wherein the total amount of one or more
compounds of formula II is about 10% by weight or less.
6. The method of claim 1 wherein T is O and a is 0-2.
7. The method of claim 6 wherein the one or more compounds of
formula III is selected from the group consisting of methanol;
ethanol; water; ethylene glycol; and diethylene glycol.
8. The method of claim 1 wherein the reaction of step (b) is
carried out in the presence of a catalyst selected from the group
consisting of sulfuric acid; paratoluene sulfonic acid; and
BF.sub.3:OEt.sub.2.
9. The method of claim 1 wherein the reaction of step (b) is
carried out in the presence of a swelling solvent.
10. The method of claim 9 wherein the swelling solvent is selected
from the group consisting of anhydrous ketones and anhydrous
C.sub.1 - C.sub.4 alcohols.
11. The method of claim 1 wherein the copolymer containing pendant
oxirane groups formed in step (a) is swollen in a swelling solvent
prior to step (b).
12. The method of claim 1 wherein the ophthalmic device material
has a refractive index of at least about 1.50; a T.sub.g from about
-20 to +25.degree. C.; and an elongation of at least 150%.
13. The method of claim 1 wherein the ophthalmic device is selected
from the group consisting of intraocular lenses; contact lenses;
keratoprostheses; corneal inlays; and corneal rings.
14. An ophthalmic device material made by the method of claim
1.
15. The method of claim 1 wherein T is O or S.
Description
[0001] This application is a continuation-in-part application of
U.S. Ser. No. 09/283,590, filed Apr. 1, 1999, which claims the
benefit of U.S. Provisional Patent Application Serial No.
60/082,833, filed Apr. 23, 1998.
FIELD OF THE INVENTION
[0002] This invention is directed to ophthalmic device materials.
In particular, this invention relates to soft, high refractive
index, acrylic ophthalmic device materials that are particularly
suited for use as intraocular lens ("IOL") materials.
BACKGROUND OF THE INVENTION
[0003] With the recent advances in small-incision cataract surgery,
increased emphasis has been placed on developing soft, foldable
materials suitable for use in artificial lenses. In general, these
materials fall into one of three categories: hydrogels, silicones,
and acrylics.
[0004] Hydrogel materials have a relatively low refractive index,
making them less desirable than other materials because of the
thicker lens optic necessary to achieve a given refractive power.
Silicone materials generally have a higher refractive index than
hydrogels, but tend to unfold explosively after being placed in the
eye in a folded position. Explosive unfolding can potentially
damage the corneal endothelium and/or rupture the natural lens
capsule. Acrylic materials are desirable because they typically
have a high refractive index and unfold more slowly or controllably
than silicone materials.
[0005] U.S. Pat. No. 5,290,892 discloses high refractive index,
acrylic materials suitable for use as an IOL material. These
acrylic materials contain, as principal components, two aryl
acrylic monomers. The IOLs made of these acrylic materials can be
rolled or folded for insertion through small incisions.
[0006] U.S. Pat. No. 5,331,073 also discloses soft acrylic IOL
materials. These materials contain as principal components, two
acrylic monomers that are defined by the properties of their
respective homopolymers. The first monomer is defined as one in
which its homopolymer has a refractive index of at least about
1.50. The second monomer is defined as one in which its homopolymer
has a glass transition temperature less than about 22.degree. C.
These IOL materials also contain a cross-linking component.
Additionally, these materials may optionally contain a fourth
constituent, different from the first three constituents, which is
derived from a hydrophilic monomer. These materials preferably have
a total of less than about 15% by weight of a hydrophilic
component.
[0007] U.S. Pat. No. 5,693,095 discloses soft, foldable acrylic
lens materials containing only two principal lens-forming
components: one aryl acrylic hydrophobic monomer and one
hydrophilic monomer. The materials comprise at least about 90% by
weight of the two principal monomeric components.
SUMMARY OF THE INVENTION
[0008] According to the present invention, high refractive index,
acrylic ophthalmic device materials are produced by a two-step
method. In the first step, at least one aryl acrylic hydrophobic
monomer is combined with up to a total of about 30% by weight of
one or more compounds of the formula 2
[0009] wherein
[0010] X is H or CH.sub.3; and
[0011] n is 1-4; and cured to form a copolymer containing pendant
oxirane groups. In the second step, the copolymer containing
pendant oxirane groups formed in step one is reacted with one or
more compounds of the formula
W-T-H (III)
[0012] wherein
[0013] W is H, CH.sub.3(CH.sub.2).sub.a, or
Z(OCH.sub.2CH.sub.2).sub.b;
[0014] b is 1-5;
[0015] Z is H, CH.sub.3, or CH.sub.3(CH.sub.2).sub.a;
[0016] a is 0-3; and
[0017] T is O, N, S; provided that if T.noteq.O. then
W.noteq.H;
[0018] to form the ophthalmic device material of the present
invention. The resulting material is suitable for use in ophthalmic
devices, such as intraocular lenses, contact lenses,
keratoprostheses, corneal rings, and corneal inlays.
DETAILED DESCRIPTION OF THE INVENTION
[0019] In the first step of the two-step method of the present
invention, a copolymer containing pendant oxirane groups is
prepared by copolymerizing a composition comprising i) one or more
aryl acrylic hydrophobic monomers of the formula 3
[0020] wherein:
[0021] X is H or CH.sub.3;
[0022] m is 0-6;
[0023] Y is nothing, O, S, or NR, wherein R is H, CH.sub.3,
C.sub.nH.sub.2n+1(n=1-10), iso-OC.sub.3H.sub.7, C.sub.6H.sub.5, or
CH.sub.2C.sub.6H.sub.5; and
[0024] Ar is any aromatic ring which can be unsubstituted or
substituted with H, CH.sub.3, C.sub.2H.sub.5, n-C.sub.3H.sub.7,
iso-C.sub.3H.sub.7, OCH.sub.3, C.sub.6H.sub.11, Cl, Br,
[0025] C.sub.6H.sub.5, or
[0026] CH.sub.2C.sub.6H.sub.5;
[0027] and (ii) a total of about 30% by weight or less of one or
more compounds of the formula 4
[0028] wherein
[0029] X is H or CH.sub.3; and
[0030] n is 1-4.
[0031] Aryl acrylic hydrophobic monomers of formula I are described
in U.S. Pat. No. 5,290,892, the entire contents of which are hereby
incorporated by reference. Preferred aryl acrylic hydrophobic
monomers for use in the materials of the present invention are
those wherein m is 2-4, Y is nothing or O, and Ar is phenyl.
[0032] Suitable monomers of formula I include 2-phenoxyethyl
acrylate; 2-phenylethylthio acrylate; 2-phenylethylamino acrylate;
phenyl acrylate; benzyl acrylate; 2-phenylethyl acrylate;
3-phenylpropyl acrylate; 3-phenoxypropyl acrylate; 4-phenylbutyl
acrylate; 4-phenoxybutyl acrylate; 4-methylphenyl acrylate;
4-methylbenzyl acrylate; 2-2-methylphenylethyl acrylate;
2-3-methylphenylethyl acrylate; 2-4-methylphenylethyl acrylate; and
their corresponding methacrylate compounds. Most preferred are
2-phenylethyl acrylate; 2-phenoxyethyl acrylate; 3-phenylpropyl
acrylate; 3-phenoxypropyl acrylate; 4-phenylbutyl acrylate;
4-phenoxybutyl acrylate; and their corresponding methacrylate
compounds. The ophthalmic device materials of the present invention
preferably contain at least one monomer of formula I that is a
methacrylate monomer (X=CH.sub.3) and at least one monomer of
formula I that is an acrylate monomer (X=H), wherein the total
amount of the acrylate monomer(s) of formula I is greater than the
total amount of methacrylate monomer(s) of formula I. In one
preferred embodiment, the monomers of formula I consist essentially
of 2-phenylethyl acrylate and 2-phenylethyl methacrylate.
[0033] The amount of aryl acrylic hydrophobic monomer will depend
upon the identity of the chosen aryl acrylic hydrophobic
monomer(s), the identity and amount of any additional ingredients
of the composition, and the desired physical properties for the
finished material. In general, the total amount of aryl acrylic
hydrophobic monomer will be about 60% by weight or greater,
preferably about 85-90% by weight.
[0034] Suitable compounds of formula II include glycidyl
methacrylate, 1-glycidyl ethyl methacrylate, 2-glycidyl ethyl
methacrylate, 1-glycidyl propyl methacrylate, 2-glycidyl propyl
methacrylate, 3-glycidyl propyl methacrylate, and their
corresponding acrylate compounds. Preferred compounds of formula II
are those wherein n=1-2. Most preferred is glycidyl
methacrylate.
[0035] The compounds of formula II can be made by methods known in
the art, with some such compounds (e.g., glycidyl methacrylate and
glycidyl acrylate) being commercially available. The identity and
amount of the compounds of formula II to be included in the
compositions of the present invention will depend upon the identity
and amount of any additional ingredients of the composition, and
the desired physical properties for the finished material. In any
event, for use in ophthalmic devices, the total concentration of
compounds of formula II should be about 30% by weight or less, and
preferably about 10% by weight or less.
[0036] In addition to at least one compound of formula I and a
total of about 30% by weight or less of one or more compounds of
formula II, the compositions of the present invention may contain
additional ingredients, such as cross-linking agents, UV
chromophores, and colorants. The total amount of such additional
ingredients is generally no more than about 10% by weight.
[0037] The copolymeric ophthalmic device materials of the present
invention are preferably cross-linked. Any ophthalmically
acceptable, terminally ethylenically unsaturated compound having
more than one unsaturated group is suitable for use in the present
copolymeric materials. Combinations of cross-linking monomers are
also suitable. Examples of suitable cross-linking agents include:
ethylene glycol dimethacrylate, diethylene glycol dimethacrylate,
allyl methacrylate, 1,3-propanediol dimethacrylate, allyl
methacrylate, 1,6-hexanediol dimethacrylate, 1,4-butanediol
dimethacrylate, and the like. A preferred cross-linking agent is
1,4-butanediol diacrylate (BDDA). Generally, the amount of the
cross-linking component will be at least about 0.1% by weight.
[0038] Many ophthalmically acceptable UV chromophores are known. A
preferred reactive UV chromophore is
2-(2'-hydroxy-3'-methallyl-5'-methyl- phenyl)benzotriazole,
commercially available as o-Methallyl Tinuvin P ("oMTP") from
Polysciences, Inc., Warrington, Pa. UV-absorbing compounds are
typically present in an amount from about 0.1-5% (weight).
[0039] Many ophthalmically acceptable blue-light absorbing
compounds are known. Suitable reactive blue-light absorbing
compounds include those described in U.S. Pat. No. 5,470,932, the
entire contents of which are hereby incorporated by reference.
Blue-light absorbers are typically present in an amount from about
0.01-0.5% (weight).
[0040] The copolymerization reaction of step one is preferably
conducted with the aid of a polymerization initiator. Suitable
polymerization initiators include temperature- and
radiation-sensitive activators. The initiator for the
copolymerization reaction of step one should be chosen such that it
is activated under conditions that do not result in opening the
oxirane groups and causing secondary reactions such as
cross-linking. Thermal initiators include peroxy free-radical
initiators, such as t-butyl (peroxy-2-ethyl)hexanoate and
di-(tert-butylcyclohexyl) peroxydicarbonate (commercially available
as Perkadox.RTM. 16 from Akzo Chemicals Inc., Chicago, Ill.). A
preferred blue-light initiator is
2,4,6-trimethyl-benzoyldiphenylophosphine oxide, commercially
available as Lucirin.RTM. TPO from BASF Corporation (Charlotte,
N.C.). For example, initiators capable of being activated by 366 nm
light at 1 mW/cm.sup.2 or by 450 nm light at 1-14 mW/cm.sup.2 are
suitable. UV-initiators are generally not suitable if the
compositions contain a UV-absorber. Likewise, blue-light initiators
are generally not suitable if the compositions contain blue-light
absorbing colorants. Initiators are typically present in relatively
small amounts (e.g., 1-3% by weight).
[0041] In the first step of the method of the present invention,
the compound(s) of formula I, the compound(s) of formula II, and
any additional ingredients are copolymerized to form a copolymer
containing pendant oxirane groups. In the second step of the method
of the present invention, the copolymer containing pendant oxirane
groups formed in step one is reacted with one or more compounds of
the formula
W-T-H (III)
[0042] wherein
[0043] W is H, CH.sub.3(CH.sub.2).sub.a, or
Z(OCH.sub.2CH.sub.2).sub.b;
[0044] b is 1-5;
[0045] Z is H, CH.sub.3, or CH.sub.3(CH.sub.2).sub.a;
[0046] a is0-3;and
[0047] T is O, N, S; provided that if T.noteq.O, then
W.noteq.H.
[0048] Preferred compounds of formula III are those wherein T=O and
a=0-2. Most preferred are methanol; ethanol; water; ethylene
glycol; diethylene glycol.
[0049] The reaction of the copolymer containing pendant oxirane
groups (the product of step one) with a compound of formula III
(step two) is preferably carried out under mild conditions (e.g.,
20-30.degree. C.), and more preferably room temperature conditions,
in the presence of a catalyst ("step two reaction catalyst").
Suitable step two reaction catalysts include mineral acids (e.g.,
dilute sulfuric acid), organic acids (e.g., paratoluene sulfonic
acid), Lewis acids (e.g., BF.sub.3:OEt.sub.2), organic bases (e.g.,
triethanolamine), and inorganic bases (e.g., dilute KOH or NaOH).
The most preferred catalyst is BF.sub.3:OEt.sub.2.
[0050] The reaction of step two is also preferably carried out in
the presence of a swelling solvent in all cases where the compound
of formula III does not itself sufficiently swell the copolymer
containing pendant oxirane groups to allow the desired reaction of
step two to proceed efficiently. The use of a swelling solvent also
minimizes secondary reactions (e.g., cross-linking). Suitable inert
swelling solvents include anhydrous ketones, such as acetone,
methylethyl ketone, and 2-pentanone. The preferred inert swelling
solvent is acetone. Reactive swelling solvents include the
anhydrous C.sub.1-C.sub.4 alcohols. The step two reaction catalyst
must be soluble in the chosen swelling solvent.
[0051] In a most preferred embodiment, there is a pre-swelling step
between steps one and two described above. The pre-swelling step
comprises soaking the copolymer containing pendant oxirane groups
(the product of step one) in a swelling solvent in the absence of
any step two reaction catalyst. Depending on the chosen swelling
solvent and the size and shape of the product of step one, the
soaking time for the pre-swelling step will generally range from
about 0.5 to about 24 hours. In those cases where a reactive
swelling solvent is chosen as the pre-swelling solvent, the
reaction of step two may be carried out in the same container as
the pre-swelling step by simply adding the step two reaction
catalyst to the container. Alternatively, the swollen copolymer
containing pendant oxirane groups may be removed from the
pre-swelling step container and added to a new or fresh swelling
solvent (or combination of swelling solvents) containing a step two
reaction catalyst.
[0052] Preferably, the identity and proportion of ingredients of
the ophthalmic device materials of the present invention are
selected so that the materials possess the following properties,
which make them particularly suitable for use in foldable IOLs.
[0053] The material preferably has a refractive index of at least
about 1.50 as measured by an Abbe' refractometer at 589 nm
(filtered halogen light source). Optics made from materials having
a refractive index lower than 1.50 are necessarily thicker than
optics of the same power which are made from materials having a
higher refractive index. As such, IOL optics made from materials
having a refractive index lower than about 1.50 generally require
relatively larger incisions for IOL implantation.
[0054] The glass-transition temperature ("Tg") of the lens
material, which affects the material's folding and unfolding
characteristics, is preferably between about -20 to +25 .degree.
C., and more preferably between about -5 and +16.degree. C. Tg is
measured by differential scanning calorimetry at 10.degree.
C./min., and is determined at the midpoint of the transition of the
heat flux curve.
[0055] The material should have an elongation of at least 150%,
preferably at least 200%, and most preferably between 300 and 600%.
This property indicates that the lens generally will not crack,
tear or split when folded. 30 Elongation of polymer samples is
determined on dumbbell shaped tension test specimens with a 20 mm
total length, length in the grip area of 4.88 mm, overall width of
2.49 mm, 0.833 mm width of the narrow section, a fillet radius of
8.83 mm, and a thickness of 0.9 mm. Testing is performed on samples
at standard laboratory conditions of 23.+-.2.degree. C. and
50.+-.5% relative humidity using an Instron Material Tester model
1122 with a 2000 gram load cell. The grip distance is set at 14 mm
and a crosshead speed is set at 20 mm/minute and the sample is
pulled to 700% elongation or until failure. The elongation (strain)
is reported as a fraction of the displacement at failure to the
original grip distance.
[0056] IOLs constructed of the materials of the present invention
can be of any design capable of being rolled or folded into a small
cross section that can fit through a relatively smaller incision.
For example, the IOLs can be of what is known as a one piece or
multipiece design, and comprise optic and haptic components. The
optic is that portion which serves as the lens and the haptics are
attached to the optic and are like arms which hold the optic in its
proper place in the eye. The optic and haptic(s) can be of the same
or different material. A multipiece lens is so called because the
optic and the haptic(s) are made separately and then the haptics
are attached to the optic. In a single piece lens, the optic and
the haptics are formed out of one piece of material. Depending on
the material, the haptics are then cut or lathed out of the
material to produce the IOL.
[0057] In addition to IOLs, the materials of the present invention
are also suitable for use as other ophthalmic devices, such as
contact lenses, keratoprostheses, and corneal inlays or rings.
[0058] The invention will be further illustrated by the following
examples which are intended to be illustrative, but not
limiting.
EXAMPLE 1
[0059] Step 1. A formulation containing 84.6 g of 2-phenylethyl
acrylate; 9.6 g of glycidyl methacrylate; 3.0 g of 1,4-butanediol
diacrylate; 1.8 g o-Methallyl Tinuvin P and 1.0 g Lucirin TPO was
mixed, placed into polypropylene molds and cured for thirty minutes
using a Palatray.TM. CU blue light source at a flux of 12-14
mW/cm.sup.2. The water content of the cured articles was then
determined gravimetrically: the sample is soaked in deionized water
overnight, removed from the water and weighed, then dried for 2
hours in an air-circulating oven at 100.degree. C. and weighed
again. The water content of the cured articles was less than
0.3%.
[0060] Step 2. The cured articles were placed into room temperature
anhydrous methanol for three hours then transferred to an anhydrous
methanol solution containing 2% by weight of BF.sub.3:OEt.sub.2 for
three days at room temperature. The articles were then removed from
the methanol solution and extracted in warm (40-50.degree. C.)
acetone for 2-4 hours, air dried at room temperature for 6 hours,
and placed in a vacuum oven (<5 mm Hg/50.degree. C.) for 4 hours
to remove any residual volatiles. The water content of the cured
articles was then evaluated again and found to be 0.9%.
EXAMPLE 2
[0061] Step 2. The cured articles formed in Step 1 of Example 1
were soaked in acetone for 3 hours, then placed in a room
temperature solution containing 1.4 g BF.sub.3:OEt.sub.2, 25.3 g
acetone, and 30.2 g of distilled water for six days. The articles
were then removed from the room temperature solution and extracted
in warm (40-50.degree. C.) acetone for 2-4 hours, air dried at room
temperature for 6 hours, and placed in a vacuum oven (<5 mm
Hg/50.degree. C.) for 4 hours to remove any residual volatiles. The
water content of the cured articles was then evaluated again and
found to be approximately 1%.
EXAMPLE 3
[0062] Step 2. The cured articles formed in Step 1 of Example 1 are
soaked for 3 hours in anhydrous acetone then placed in a room
temperature solution containing 1.4 g BF.sub.3:OEt.sub.2, 25.3 g
anhydrous acetone, and 30.2 g of anhydrous ethanol for six days.
The articles are then removed from the room temperature solution
and extracted in warm (40-50.degree. C.) acetone for 2-4 hours, air
dried at room temperature for 6 hours, and placed in a vacuum oven
(<5 mm Hg/50.degree. C.) for 4 hours to remove any residual
volatiles.
EXAMPLE 4
[0063] Step 2. The cured articles formed in Step 1 of Example 1 are
soaked for 3 hours in anhydrous acetone (or a combination of
anhydrous acetone and anhydrous ethylene glycol), then placed in a
room temperature solution containing 1.4 g BF.sub.3:OEt.sub.2, 25.3
g anhydrous acetone, and 30.2 g of anhydrous ethylene glycol for
six days. The articles are then removed from the room temperature
solution and extracted in warm (40-50.degree. C.) acetone for 2-4
hours, air dried at room temperature for 6 hours, and placed in a
vacuum oven (<5 mm Hg/50.degree. C.) for 4 hours to remove any
residual volatiles.
EXAMPLE 5
[0064] Step 2. The cured articles formed in Step 1 of Example 1 are
soaked for 3 hours in anhydrous acetone (or a combination of
anhydrous acetone and anhydrous diethylene glycol), then placed in
a room temperature solution containing 1.4 g BF.sub.3:OEt.sub.2,
25.3 g anhydrous acetone, and 30.2 g of anhydrous diethylene glycol
for six days. The articles are then removed from the room
temperature solution and extracted in warm (40-50.degree. C.)
acetone for 2-4 hours, air dried at room temperature for 6 hours,
and placed in a vacuum oven (<5 mm Hg/50.degree. C.) for 4 hours
to remove any residual volatiles.
EXAMPLE 6
[0065] Step 2. The cured articles formed in Step 1 of Example 1 are
soaked for 3 hours in anhydrous acetone (or a combination of
anhydrous acetone and anhydrous monomethoxy diethylene glycol),
then placed in a room temperature solution containing 1.4 g
BF.sub.3:OEt.sub.2, 25.3 g anhydrous acetone, and 30.2 g of
anhydrous monomethoxy diethylene glycol for six days. The articles
are then removed from the room temperature solution and extracted
in warm (40-50.degree. C.) acetone for 2 -4 hours, air dried at
room temperature for 6 hours, and placed in a vacuum oven (<5 mm
Hg/50.degree. C.) for 4 hours to remove any residual volatiles.
EXAMPLE 7
[0066] Step 1. A formulation containing 60.6 g of 2-phenylethyl
acrylate; 24.0 g of 2-phenylethyl methacrylate; 9.6 g of glycidyl
methacrylate; 3.0 g of 1,4-butanediol diacrylate; 1.8 g o-Methallyl
Tinuvin P and 1.0 g Lucirin TPO is mixed, placed into polypropylene
molds and cured for thirty minutes using a Palatray.TM. CU blue
light source at a flux of 12-14 mW/cm.sup.2.
[0067] Step 2. The cured articles obtained in Step 1 are soaked for
3 hours in anhydrous acetone, then placed in a room temperature
solution containing 1.5 g BF.sub.3:OEt.sub.2, 25 g anhydrous
acetone (or anhydrous methylethyl ketone or anhydrous 2-pentanone),
and 30 g of anhydrous methanol (or distilled water, anhydrous
ethanol, anhydrous ethylene glycol, anhydrous diethylene glycol or
anhydrous monomethoxy diethylene glycol) for six days. The articles
are then removed from the room temperature solution and extracted
in warm (40-50.degree. C.) acetone for 2-4 hours, air dried at room
temperature for 6 hours, and placed in a vacuum oven (<5 mm
Hg/50.degree. C.) for 4 hours to remove any residual volatiles.
[0068] The invention has been described by reference to certain
preferred embodiments; however, it should be understood that it may
be embodied in other specific forms or variations thereof without
departing from its spirit or essential characteristics. The
embodiments described above are therefore considered to be
illustrative in all respects and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description.
* * * * *